US20090163948A1

Movatterモバイル変換

Info

Publication number: US20090163948A1
Application number: US12/340,818
Authority: US
Inventors: Takamitsu Sunaoshi; Makoto Jinno; Ryohei Katsuki
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2007-12-21
Filing date: 2008-12-22
Publication date: 2009-06-25
Also published as: JP2009148859A; JP5017076B2

Abstract

A medical manipulator system includes a manipulator including a working unit having a distal-end working unit, the attitude of which can be changed by a motor, and a controller for controlling the manipulator. When the controller performs an origin return process for moving a gripper of the distal-end working unit to an origin position at an end of an operating range thereof, the controller issues a first control target value to the motor indicative of a virtual position beyond the origin. Thereafter, the controller issues a second control target value to the motor indicative of the origin. The first control target value represents a position, which is over from the origin P0 by a distance greater than a value corresponding to an error ε between a control target position for the gripper and the actual position thereof.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manipulator system including a manipulator having an actuating unit, which can be actuated by an actuator in order to change the attitude thereof, and a controller for controlling the manipulator. The present invention also concerns a method of controlling such a manipulator.

2. Description of the Related Art

According to a laparoscopic surgical operation process, small holes are opened in the abdominal region, for example, of a patient, and an endoscope, forceps or manipulators, etc., are inserted into the holes. A surgeon performs a surgical operation on the patient with the manipulators or forceps while watching an image captured by the endoscope and displayed on a display monitor. Since the laparoscopic surgical operation process does not require a laparotomy to be performed, it is less burdensome on the patient and greatly reduces the number of days that the patient is required to spend before recovering from the operation and being released from the hospital. Thus, the range of surgical operations to which such a laparoscopic surgical process is applicable is expected to increase.

As disclosed in JP 2004-105451 A, for example, a manipulator system comprises a manipulator and a controller for controlling the manipulator. The manipulator comprises a manually operable operating unit and a working unit replaceably mounted on the operating unit.

The working unit (instrument) comprises a long joint shaft and a distal-end working unit (also referred to as an end effector) mounted on the distal end of the joint shaft. The operating unit includes actuators (motors) therein for actuating the working unit through wires. The wires are wound around respective pulleys disposed in a proximal end portion of the working unit. The controller energizes the motors of the operating unit in order to cause the pulleys to move the wires back and forth.

Various different working units, including a gripper, scissors, an electrosurgical knife, an ultrasonic knife, a medical drill, etc., are used to perform respective surgical techniques in a laparoscopic surgical operation process. Such working units are detachably mounted on the operating unit. When the working units are selectively mounted on the operating unit, the pulleys in the proximal end of the working unit are held in engagement with the rotational shafts of the motors in the operating unit.

In a system where different working units are selectively connected to one operating unit, it is necessary to establish a motor phase, which serves as a common axis position for allowing all of the working units to be detachably mounted on the operating unit (see, for example, JP 2004-105451 A and JP 08-071072 A). The established motor phase is referred to as an origin or initial position.

The motors and the working unit are operatively coupled to each other by wires. Therefore, even when the motors are returned to their original states, the working unit may not fully be returned to its initial position, but may suffer from a positional error, due to inevitable stretching of the wires and friction between the various parts.

In order to prevent the working unit from suffering from positional errors, a sensor may be provided at a location corresponding to the working unit, rather than the motors, and the working unit may be controlled by a feedback loop so as to return the working unit to its initial position based on detected signals from the sensor (see, for example, JP 2002-261496 A and JP 2006-149468 A).

Medical manipulators should be designed based on certain desirable conditions owing to the fact that the working units thereof are inserted into body cavities. According to such desirable conditions, a medical manipulator should be as small and light as possible, should be mounted replaceably on an operating unit, should be able to be cleaned and sterilized easily, and should not include electrical devices therein, except for an electrosurgical knife or the like.

According to the inventions disclosed in JP 2002-261496 A and JP 2006-149468 A, for returning the working unit reliably to its initial position or origin, the sensor is provided at a location corresponding to the working unit. If the sensor is incorporated in a medical manipulator, then the working unit becomes large and heavy. Particularly, if the distal end of the working unit is unduly heavy, the working unit is subject to a large moment and cannot easily be operated. Also, the working unit incorporating the sensor cannot easily be replaced, because the sensor needs to be electrically connected. In addition, in such a case, the working unit becomes difficult to clean and sterilize.

SUMMARY OF THE INVENTION

It is one of the objects of the present invention to provide a manipulator system and a method of controlling a manipulator for reliably returning a working unit to an origin or initial position, without the need for an electrical device such as a sensor or the like to be used in combination with the working unit.

According to one aspect of the present invention, a manipulator system is provided comprising a manipulator having an actuator and an actuating unit, the actuating unit being actuatable by the actuator to change an attitude thereof, and a controller for controlling the manipulator in order to perform an origin return process for moving the actuating unit to an end of an operating range thereof, by issuing a first control target value to the actuator indicative of a virtual position beyond the end of the operating range, and thereafter issuing a second control target value to the actuator indicative of the end of the operating range.

According to another aspect of the present invention, a method of controlling a manipulator also is provided having an actuating unit which can be actuated by an actuator in order to change an attitude thereof, comprising performing an origin return process for moving the actuating unit to an end of an operating range thereof, by issuing a first control target value to the actuator indicative of a virtual position beyond the end of the operating range, and thereafter issuing a second control target value to the actuator indicative of the end of the operating range.

When the first control target value indicative of the virtual position is issued, the actuating unit reliably reaches the end of its operating range. Therefore, the actuating unit can reliably be returned to its origin without the need for an electric device such as a sensor in combination with the actuating unit. At this time, stresses are not yet removed from the actuating unit, the actuator, and a transmitting member. Therefore, the second control target value, which indicates the end of the operating range, is subsequently issued in order to remove such stresses.

Even if the actuator and the actuating unit are operatively connected to each other by the transmitting member, which inevitably experiences stretching, and by various parts that cause friction, the actuating unit can accurately be returned to the origin thereof, thereby eliminating error.

The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a manipulator system according to an embodiment of the present invention;

FIG. 2 is a perspective view showing possible combinations of the manipulator system according to the embodiment of the present invention;

FIG. 3 is a side elevational view of a manipulator of the manipulator system, with a working unit and an operating unit being separated from each other;

FIG. 4 is a perspective view of the operating unit;

FIG. 5 is a perspective view of a distal-end working unit of the working unit;

FIG. 6 is an exploded perspective view of the distal-end working unit;

FIG. 7 is a block diagram of a controller of the manipulator system;

FIG. 8 is a flowchart of a processing sequence of the manipulator system;

FIG. 9 is a flowchart of a sequence of an origin return process;

FIG. 10 is a graph showing control target values and changes in the angle of a gripper in the distal-end working unit during the origin return process;

FIG. 11 is a schematic perspective view showing a motor and the gripper in a first state in the origin return process;

FIG. 12 is a schematic perspective view showing the motor and the gripper in a second state in the origin return process;

FIG. 13 is a schematic perspective view showing the motor and the gripper at a time when the origin return process is ended; and

FIG. 14 is a schematic perspective view of a surgical robot system with the working unit connected to the distal end of a robot arm.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Amanipulator system500 according to an embodiment of the present invention will be described below with reference toFIGS. 1 through 14. The manipulator system500 (seeFIG. 1) may be used in a laparoscopic surgical operation process or the like.

As shown inFIG. 1, themanipulator system500 comprises amanipulator10 and acontroller514 for controlling themanipulator10. Themanipulator10 and thecontroller514 are detachably connected to each other by a connector.

Themanipulator10 includes a distal-end working unit12 for gripping a portion of a living tissue, or for gripping a curved needle or the like, for performing a given surgical treatment. Themanipulator10 comprises an operating unit (first portion)14 and a working unit (second portion)16 as basic components. Thecontroller514 electrically controls themanipulator10, and is connected by the connector to acable61 that extends from the lower end of agrip handle26 of theoperating unit14.

As shown inFIG. 2, themanipulator system500 may have various configurations selectively. Specifically, working

units

16a,16b,16c,16dare available as variations for the workingunit16, and can selectively be mounted on the operatingunit14. The surgeon or operator who handles themanipulator system500 can select one of the working

units

16a,16b,16c,16d,depending on the surgical procedure that the surgeon intends to perform, and the degree to which the surgeon is familiar with the working units. The workingunit16bhas scissors as the distal-end working unit12 thereof. The workingunit16chas a blade-like electrosurgical knife as the distal-end working unit12 thereof. The workingunit16dhas a hook-like electrosurgical knife as the distal-end working unit12 thereof. The working

units

16a,16b,16c,16dhave

common pulleys

50a,50b,50c(seeFIG. 1) disposed within theconnectors15 thereof.

Themanipulator10, which comprises the operatingunit14 and the workingunit16a,will be described below.

The distal-end working unit12 of themanipulator10 serves to grip a portion of a living tissue, a curved needle, or the like, for performing a given surgical treatment. The distal-end working unit12 is usually referred to as a gripping forceps or a needle driver (needle holder).

As shown inFIGS. 1 and 3, themanipulator10 includes the operatingunit14, which is held and operated by hand, and the workingunit16, which is detachably mounted on the operatingunit14.

In the following descriptions, transverse directions inFIG. 1 shall be referred to as X directions, vertical directions as Y directions, and longitudinal directions of a hollowjoint shaft48 as Z directions. In the X direction, the rightward direction as viewed from the distal end is referred to as an X1 direction, and the leftward direction as an X2 direction. In the Y direction, the upward direction is referred to as a Y1 direction, and the downward direction as a Y2 direction. In the Z direction, the forward direction is referred to as a Z1 direction, and the rearward direction as a Z2 direction. Unless otherwise noted, these directions represent directions of themanipulator10 when the manipulator is placed in a neutral attitude. The definitions of the above directions are for illustrative purposes only, and themanipulator10 can be used in any orientation. For example, themanipulator10 may be used upside down.

The workingunit16 includes the distal-end working unit12 for performing a working operation, aconnector15 connected to anactuator block30 of the operatingunit14, and an elongate hollowjoint shaft48 coupling the distal-end working unit12 and theconnector15 to each other. When a predetermined action is performed on theactuator block30, the workingunit16 can be separated from the operatingunit14, so that the workingunit16 can be cleaned, sterilized, and/or serviced for maintenance.

The distal-end working unit12 and thejoint shaft48, which are small in diameter, can be inserted into abody cavity22 through atrocar20 in the form of a hollow cylinder mounted in an abdominal region or the like of the patient. The distal-end working unit12 is actuated by the operatingunit14 in order to perform various surgical techniques to remove, grip, suture, or ligate an affected area of the patient's body inside thebody cavity22.

The operatingunit14 includes agrip handle26 gripped by hand, abridge28 extending from an upper portion of thegrip handle26, and anactuator block30 connected to a distal end of thebridge28.

As shown inFIG. 1, the grip handle26 of the operatingunit14 extends in the Y2 direction from the end of thebridge28, and has a length suitable for being gripped by a human hand. The grip handle26 has atrigger lever32 as an input means, acomposite input unit34, and aswitch36.

Thebridge28 has anLED29 in an easily visually recognizable position on an upper surface or a side surface thereof. TheLED29 is an indicator for indicating a controlled state of themanipulator10. TheLED29 is of a size large enough to be easily visually recognizable by the operator, and yet is sufficiently small and light so as not to interfere with the operation of themanipulator10. In the present embodiment, theLED29 is located in a visually recognizable position substantially centrally on the upper surface of thebridge28.

Thecable61 has an end connected to the lower end of the grip handle26 and an opposite end connected to thecontroller514. The grip handle26 and thecable61 may be connected to each other by a connector.

Thecomposite input unit34 serves as a composite input means for giving rotational commands in rolling directions (shaft rotating directions) and yawing directions (left and right directions) to the distal-end working unit12. For example, thecomposite input unit34 may serve as a first input means movable in the shaft rotating directions for entering commands in rolling directions, and a second input means movable in left and right directions for entering commands in yawing directions. Thetrigger lever32 serves as an input means for giving opening and closing commands to a gripper (actuating unit)59 (seeFIG. 1) of the distal-end working unit12. Thecontroller514 holds internal signals indicative of angles of the

motors

40,41,42 corresponding to a roll axis, a yaw axis, and a gripper axis respectively. Based on signals from thecomposite input unit34 and thetrigger lever32, thecontroller514 changes the internal signals to equalize the angles of the

motors

40,41,42.

Theswitch36 serves as an input means for selectively enabling and disabling themanipulator10.

As shown inFIGS. 3 and 4, thecomposite input unit34 and thetrigger lever32 are associated with

input sensors

39a,39b,39cfor detecting operational quantities. The

input sensors

39a,39b,39csupply detected operational signals to thecontroller514.

Thetrigger lever32 is disposed slightly below thebridge28 and projects in the Z1 direction. Thetrigger lever32 is disposed in a position where it can easily be operated by the index finger of the hand that grips thegrip handle26.

Thetrigger lever32 is operatively coupled to the grip handle26 by anarm98, and is movable toward and away from thegrip handle26.

Theswitch36 serves as an operating mechanism movable toward and away from thegrip handle26. Thetrigger lever32 and theswitch36 extend in the Z1 direction away from the grip handle26 and are located closely together, i.e., juxtaposed in the longitudinal direction (Y direction) of thegrip handle26. Theswitch36 is disposed directly below thetrigger lever32 in the Y2 direction, with athin plate130 interposed between theswitch36 and thetrigger lever32. Thethin plate130 extends from the grip handle26 in the Z1 direction.

Theswitch36 comprises an alternate switch having atrigger knob36a.Theswitch36 operates as follows: When thetrigger knob36ais pushed toward the grip handle26 in the Z2 direction, theswitch36 is locked in an ON state, and thetrigger knob36ais held in a position near thegrip handle26. When thetrigger knob36ais pushed again toward thegrip handle26, theswitch36 is released from the ON state into an OFF state. Thetrigger knob36ais automatically returned in the Z1 direction to a position remote from the grip handle26 under the bias of a resilient member (not shown).

Operation and stop modes of themanipulator10 are changed by theswitch36. Specifically, thecontroller514, which reads the states of theswitch36, places themanipulator10 in an operational mode when theswitch36 is in the ON state, operates themanipulator10 under an automatic origin return process in order to return the

motors

40,41,42 to the origin when theswitch36 changes from the ON state to the OFF state, and places themanipulator10 in a stop mode after the

motors

40,41,42 have been returned to their origin positions. The operational mode is a mode in which the distal-end working unit12 is actuated based on operations of thetrigger lever32 and thecomposite input unit34. The stop mode is a mode in which the distal-end working unit12 is inactivated in a predetermined origin attitude.

Thecontroller514 distinguishes the above modes and processes from each other, and changes the energized state of theLED29 based on the distinguished modes and processes.

Theactuator block30 houses therein the

motors

40,41,42, which are associated respectively with mechanisms having three degrees of freedom in the distal-end working unit12. The

motors

40,41,42 are juxtaposed along the direction in which thejoint shaft48 extends. The

motors

40,41,42 are small in size and diameter, and theactuator block30, which houses the

motors

40,41,42 therein, is of a flat compact shape. Theactuator block30 is disposed below an end of the operatingunit14 in the Z1 direction. The

motors

40,41,42 are energized under the control of thecontroller514 based on actions made by the operator on the operatingunit14.

The

motors

40,41,42 are combined with respective angle sensors (detecting means)43,44,45 for detecting respective angular displacements of the

motors

40,41,42. The

angle sensors

43,44,45 supply detected angle signals to thecontroller514. The

angle sensors

43,44,45 may comprise rotary encoders, for example.

The workingunit16 includes on its proximal end theconnector15 connected to theactuator block30 and the hollowjoint shaft48 that extends from theconnector15 in the Z1 direction. Theconnector15 houses pulleys (driven members)50a,50b,50crotatably disposed therein, which are connected respectively to

50a,50b,50ceach have respective couplings.

Wires (transmitting members)52,53,54 are trained around the

pulleys

50a,50b,50c,respectively, and extend through aspace48a(seeFIG. 5) in the hollowjoint shaft48 to the distal-end working unit12. The

wires

52,53,54 may be of the same type and diameter.

The workingunit16 can be separated from the operatingunit14 by carrying out a given action on theactuator block30, so that the workingunit16 can be cleaned, sterilized, or serviced for maintenance. The workingunit16 may be replaced with another type of working unit (seeFIG. 2). Depending on the nature of the surgical procedure to be carried out using themanipulator10, a workingunit16 whosejoint shaft48 has a different length or whose distal-end working unit12 has a different mechanism may be mounted on the operatingunit14.

The workingunit16 is detachably mounted on the operatingunit14. When the workingunit16 is mounted on the operatingunit14, the

rotatable shafts

40a,41a,42aof the

motors

40,41,42 are held in axially aligned engagement with the lower ends of the

pulleys

50a,50b,50c.Specifically, the lower ends of the

pulleys

50a,50b,50chave respective criss-crossed joint teeth thereon, and the upper ends of the

rotatable shafts

40a,41a,42ahave respective criss-crossed joint recesses defined therein. When the workingunit16 is mounted on the operatingunit14, the criss-crossed joint teeth on the lower ends of the

pulleys

50a,50b,50care fitted into the respective joint recesses provided in the upper ends of the

rotatable shafts

40a,41a,42a,for thereby reliably transferring rotational forces from the

motors

40,41,42 to the

pulleys

50a,50b,50c.The joint teeth and the joint recesses are not limited to criss-crossed shapes, but may comprise other types of interfitting shapes as well.

Theconnector15 has an ID (identification)holder104 for holding an ID capable of individually identifying the workingunit16.

TheID holder104 may be a wireless ID holder such as an RFID (Radio Frequency Identification) holder, a non-contact detection ID holder such as an optical ID holder, which may be a bar code, a matrix two-dimensional code, or the like, or a contact detection ID holder such as a sequence of small protrusions or the like.

The ID held by theID holder104 includes a value for identifying each of the workingunits16athrough16d.

TheID holder104 does not need to be electrically energized directly, and hence theconnector15 and the workingunit16 have no electric contacts. Therefore, when the workingunit16 is dismounted from the operatingunit14, the workingunit16 can easily be cleaned or sterilized. Specifically, all of the electric components, including the motors, the switches, and the sensors, are placed within the operatingunit14, whereas only mechanical components including thejoint shaft48 and the distal-end working unit12 are provided in the workingunit16, so that the workingunit16 can efficiently be cleaned. It is preferable for the workingunit16 and the operatingunit14 to be separable from each other, since under use the units will be smeared differently with different materials, thus requiring the units to be cleaned and serviced for maintenance using different techniques. Since no electric components are included in the workingunit16, the workingunit16 can easily be replaced on the operatingunit14.

Since the distal-end working unit12 is free of electric components, it is small in size, small in diameter, and light in weight. Furthermore, since the weight at the distal end of the distal-end working unit12 is small, the distal-end working unit12 is subject to a small moment, thus allowing themanipulator10 to be operated with ease.

The operatingunit14 has an ID relay unit (identifying means)106 for reading the ID held by theID holder104 and supplying the read ID to thecontroller514. TheID relay unit106 may comprise an RFID transmitting and receiving circuit, a photocoupler, or the like.

Theactuator block30 has a pair oflevers206 pivotally mounted on respective outer side surfaces thereof. Thelevers206 haverespective wedges206aon upper inner surfaces thereof, which engagerespective teeth200 on outer side surfaces of theconnector15 when theconnector15 is mounted on theactuator block30. Thelevers206 are normally biased by a resilient member to hold thewedges206ain locking engagement with theteeth200. For removing theconnector15 from the operatingunit14, the operator pushes the lower portions of thelevers206 in order to tilt the upper portions thereof outwardly, thereby releasing theedges206afrom engagement with theteeth200. Theconnector15 can now be pulled upwardly in the Y1 direction and detached from the operatingunit14. Theactuator block30 has threealignment pins212 that project upwardly from the upper surface thereof. Theconnector15 has threefitting holes202 defined therein, which open in a downward direction. When the alignment pins212 are fitted respectively in thefitting holes202, theconnector15 is stably supported on theactuator block30. For installing theconnector15 on the operatingunit14, the alignment pins212 are positioned in alignment with the respectivefitting holes202, and then theconnector15 is pressed downwardly in the Y2 direction toward theactuator block30. As theconnector15 is displaced toward theactuator block30, the upper portions of thelevers206 are spread outwardly by theteeth200. When thewedges206amove past theteeth200, thelevers206 snap back under the resiliency of the resilient member, thereby bringing thewedges206ainto locking engagement with theteeth200, so that theconnector15 becomes locked in place on theactuator block30.

A working unit detecting means107 for detecting whether theconnector15 has been placed on theactuator block30 is disposed on anupper surface30bof theactuator block30, at an end thereof in the Z2 direction. The working unit detecting means107 comprises alight emitter107aand alight detector107b,which are positioned in confronting relation to each other. When a portion of the rear end of theconnector15 is inserted between thelight emitter107aand thelight detector107b,theconnector15 blocks light emitted from thelight emitter107atoward thelight detector107b,thereby detecting that theconnector15 has been mounted on theactuator block30. Thelight emitter107aand thelight detector107bconfront each other in the X direction and are disposed closely to each other. Thelight emitter107amay be an LED, and thelight detector107bmay be a photodiode, for example.

As shown inFIGS. 5 and 6, the distal-end working unit12 incorporates therein mechanisms providing three degrees of freedom. These mechanisms include a mechanism (tilting mechanism, pivot axis) having a first degree of freedom for angularly moving a distal end portion, which is positioned in front of a first rotational axis Oy extending along the Y direction, in yawing directions about the first rotational axis Oy, a mechanism (rolling mechanism) having a second degree of freedom for angularly moving the distal end portion in rolling directions about a second rotational axis Or extending along the Z direction, and a mechanism having a third degree of freedom for opening and closing thegripper59 on the distal end about a third rotational axis Og extending along the X direction.

The first rotational axis Oy of the mechanism having the first degree of freedom may be an axis about which the distal end portion is angularly movable, and not parallel to an axis C that extends from the proximal to the distal end of thejoint shaft48. The second rotational axis Or of the mechanism having the second degree of freedom may be an axis along which the distal end (the gripper59) of the distal-end working unit12 extends and about which thegripper59 is rotatable in the rolling directions.

Thegripper59 is fully closed when in the origin position and can be opened through a given angle from the origin. Although thegripper59 is shown as being a one-sided openable type, thegripper59 may also be a double-sided openable type. A one-sided openable type refers to a structure in which one of a pair of pinching members of thegripper59 is openable and closable with respect to the other pinching member, which is fixed. A double-sided openable type refers to a structure in which both of the pinching members of thegripper59 are openable and closable with respect to each other.

The distal-end working unit12 is actuated by the

wires

52,53,54, which are trained around corresponding

tubular members

60c,60b,60athat are supported rotatably in the distal end of thejoint shaft48.

When the

wires

52,54 are moved, gears51,55 coaxial with the

tubular members

60c,60b,60aare rotated, thereby causing a face gear, not shown, to rotate thegripper59 in the rolling directions. When thewire54 is moved, thegear51 is rotated, thereby causing aface gear57 and agear58 to open and close thegripper59. When the

wires

52,53,54 are moved, amain shaft62 is angularly moved in order to turn thegripper59 in the yawing directions.

Internal structural details of thecontroller514 will be described below with reference toFIG. 7.

As shown inFIG. 7, thecontroller514 includes aprocessor110, apower supply112, aprotector114, and adriver116. Thepower supply112 regulates electric power supplied from anexternal power supply119 and supplies the regulated electric power to various components in thecontroller514. Thepower supply112 charges abattery112a,and automatically switches to thebattery112ain the event that electrical power cannot be supplied from theexternal power supply119. Thepower supply112 thus operates as an uninterruptible power supply. Thebattery112ais connected in parallel with a transformer-rectifier assembly in thepower supply112.

Theprotector114 shuts off electric power supplied to themanipulator10 based on various items of information supplied thereto. When theprotector114 shuts off the electric power supplied to themanipulator10, themanipulator10 immediately stops operation.

Theprocessor110 is electrically connected to the

angle sensors

43,44,45, the

input sensors

39a,39b,39c,and theswitch36. Based on signals from these sensors and theswitch36, theprocessor110 determines how to operate themanipulator10, supplies a predetermined command signal to thedriver116, and controls an operational state display unit to display a certain operational state. Theprocessor110 also is connected electrically to theLED29 in order to control the energized state thereof. Theprocessor110 is further electrically connected to various switches on the front panel of thecontroller514 for controlling the switches. Theprocessor110 comprises a CPU, a ROM, a RAM, etc., and performs given software processes by reading and executing a program.

Thedriver116 is electrically connected to the

motors

40,41,42, and energizes the

motors

40,41,42 based on commands from theprocessor110. A drive system for the

motors

40,41,42 determines operational angle command values for the distal-end working unit12 based on signals from the

input sensors

39a,39b,39c,determines differences between the operational angle command values and the angle signals from the

angle sensors

43,44,45, performs a predetermined compensating process based on such differences, and supplies command signals to thedriver116.

Therefore, the drive system for the

motors

40,41,42 is of a closed loop configuration.

Theprocessor110 includes an ID recognizer (identifying means)120 and anorigin return controller122. TheID recognizer120 recognizes the ID of theID holder104.

Operation of themanipulator system500 will be described below with reference to the flowchart shown inFIG. 8.

Themanipulator system500 operates under the general control of theprocessor110 of thecontroller514, and basically performs an operation sequence according to the flowchart shown inFIG. 8. The operation sequence according to the flowchart shown inFIG. 8 is repeatedly carried out during predetermined control periods. It is assumed that the operation sequence is performed in the order of the indicated step numbers, unless otherwise indicated.

In step S11 shown inFIG. 8, theprocessor110 reads output signals from angle detectors in the operatingunit14 and the

In step S12, theprocessor110 recognizes input signals from the command input means and theswitch36.

In step S13, theprocessor110 determines a control mode for themanipulator10 based on the input signals recognized by theprocessor110.

In step S14, theprocessor110 determines an operating process and control target values for the

motors

40,41,42 according to the determined control mode.

In step S15, theprocessor110 calculates motor output signals from the control target values and the angle signals from the

angle sensors

43,44,45 according to a control process such as a PID control process, and outputs the calculated motor output signals to thedriver116.

In step S16, theprocessor110 compares various defined conditions with the angle signals from the

angle sensors

43,44,45, and determines the state of themanipulator10.

In step S17, theprocessor110 outputs signals to the lamps on thecontroller514, based on the determined state of themanipulator10.

The origin return process will be described below with reference toFIGS. 9 through 13. The origin return process is performed by thecontroller514 based on actions made on theswitch36 and the switches on thecontroller514, and the origin return process is divided into a first-stage origin return process during an interval T1 (seeFIG. 10) and a second-stage origin return process during an interval T2. With reference toFIG. 9, a process for automatically returning thegripper59 to an end of the operating range thereof, i.e., to an origin P0 (seeFIG. 10), will mainly be described below. Since themotor40 is feedback-controlled based on the angle signal from theangle sensor43, at least in a static state, it can be assumed that the angular displacement of themotor40 is substantially free of positional errors from the control target value.

In step S101 shown inFIG. 9, thecontroller514 monitors the state of theswitch36 in order to confirm whether an origin return command has been generated or not. If an origin return command has been generated by theswitch36, then control goes to step S102. If an origin return command has not been generated by theswitch36, then thecontroller514 waits for an origin return command to be generated.

In step S102, thecontroller514 determines whether or not preparations for starting the origin return process have been made. If preparations for starting the origin return process have been made, then control goes to step S104. If preparations for starting the origin return process have not been made, then thecontroller514 performs a given preparatory process, in step S103, and then waits until it is determined again whether preparations for the origin return process have been started.

The preparations for starting the origin return process refer to conditions indicating that a predetermined servo flag is ON, that a first-stage origin return process flag and a second-stage origin return process flag are OFF, that a second-stage origin return process completion flag is OFF, and that the connected workingunit16 corresponds to a given type. The servo flag is a flag indicating that the

motors

40,41,42 can be servo-controlled. The first-stage origin return process flag and the second-stage origin return process flag are flags indicating that the first-stage origin return process during the interval T1 and the second-stage origin return process during the interval T2 are being carried out. A first-stage origin return process completion flag and a second-stage origin return process completion flag are flags indicating that the first-stage origin return process during the interval T1 and the second-stage origin return process during the interval T2 have finished. The flags make the corresponding indications thereof affirmative when the flags are ON, and negative when the flags are OFF.

In step S104, thecontroller514 determines whether the first-stage origin return process has finished or not. Specifically, thecontroller514 monitors the first-stage origin return process completion flag in step S104. If the first-stage origin return process completion flag is ON, then control goes to step S106. If the first-stage origin return process completion flag is OFF, then control goes to step S105.

In step S105, thecontroller514 sets given parameters for performing the first-stage origin return process. Specifically, thecontroller514 acquires a present process start angle, establishes a first control target value P1, and turns the first-stage origin return process flag ON.

In step S106, thecontroller514 sets given parameters for performing the second-stage origin return process. Specifically, thecontroller514 acquires a present process start angle at that time (which essentially is identical to the first control target value P1), establishes a second control target value P2, and turns the second-stage origin return process flag ON. The second control target value P2 is in agreement with the origin P0. After step S105 or S106, control goes to step S107.

In step S107, thecontroller514 generates a target value for a PTP (Point-to-Point) movement process. The PTP movement process is a process for moving thegripper59 along a target trajectory, which is generated to interconnect the present position and the target position. The PTP movement process is realized by linear interpolation, trapezoidal speed interpolation, or an S-shaped acceleration/deceleration trajectory between the present position and the target position.

In step S108, thecontroller514 performs control calculations for performing the PTP movement process. Processing from steps S105 through S108 may be carried out only initially during the first-stage origin return process and during the second-stage origin return process.

In step S109, thecontroller514 outputs a drive signal to themotor40 based on the result of the control calculations.

In step S110, thecontroller514 determines the origin return process. Specifically, during the first-stage origin return process, thecontroller514 monitors whether or not the detected value from theangle sensor43 has reached the first control target value P1. When the detected value from theangle sensor43 reaches the first control target value P1, thecontroller514 turns off the first-stage origin return process flag, while turning on the first origin return process completion flag.

During the second-stage origin return process, thecontroller514 monitors whether or not the detected value from theangle sensor43 has reached the second control target value P2 (=P0). When the detected value from theangle sensor43 has reached the second control target value P2, thecontroller514 turns off the second-stage origin return process flag, while turning on the second origin return process completion flag. Thecontroller514 may determine the origin return process with a given latitude in view of errors.

In step S111, thecontroller514 determines whether or not the origin return process has finished. Specifically, if both the first origin return process completion flag and the second origin return process completion flag are ON, then thecontroller514 judges that the origin return process has finished, and terminates the sequence shown inFIG. 9. Otherwise, control goes back to step S104.

If the control target value at the start of the origin return process is equal to the first control target value P1, then the first-stage origin return process is finished immediately, and the origin return process starts essentially from the second-stage origin return process.

If the control target value at the start of the origin return process is a value between the first control target value P1 and the limit value Px (i.e., if thegripper59 is to be closed forcibly), then thecontroller514 may turn the first-stage origin return process completion flag ON between step S102 and step S104, thereby simplifying the origin return process.

If a working unit is mounted on the operatingunit14, which does not need the first-stage origin return process during the interval T1 and the second-stage origin return process during the interval T2, e.g., a workingunit16chaving a blade-like electrosurgical knife, then thecontroller514 may turn the first-stage origin return process completion flag ON between step S102 and step S104, for performing an ordinary origin return process.

If the condition indicating that the second-stage origin return process completion flag is OFF is omitted from the conditions in step S102, then the origin control process can be carried out again. Such processing may be performed based on certain actions of the operator, when the origin control process experiences trouble due to an unexpected incident. Step S101 shown inFIG. 9 corresponds to step S12 shown inFIG. 8, steps S103 through S106 correspond to step S13, steps S107 and S108 correspond to step S14, and steps S109 through S110 correspond to step S15, respectively.

Operation of themanipulator10 according to the above origin return process will be described below.

When the origin return process is started, thegripper59 is open, as indicated by the imaginary lines inFIG. 11. InFIGS. 11 through 13, it is assumed that the speed reduction ratio between themotor40, thepulley50aand arotor300 of thegripper59 is 1. Mechanisms with respect to the yaw and roll axes have been omitted from illustration. The mechanism for opening and closing thegripper59 is shown in a simplified form. Thepulley50aand therotor300 are marked with

respective markers

302,304 for more easily understanding the angles thereof. Thepulley50aand therotor300 are placed in their origin positions P0 when the

markers

302,304 are oriented in the Z2 direction.

After the start of the origin return process, when therotor300 and thepulley50aare turned counterclockwise in a direction to close thegripper59 until time t1 (seeFIG. 10) is reached, thepulley50areaches the origin P0. At this time, therotor300 does not reach the origin P0 but suffers from an error ε due to stretching of thewire52 as well as friction between the various parts. InFIGS. 11 and 12, a portion of thewire52, which is elongated under strong tension, is shown as being thinner, whereas a portion of thewire52, which is held under a weak tension, is shown as being thicker.

If the error ε is not removed, then the handling of themanipulator10 tends to feel odd or unusual. If the error ε is unduly large, then the operator finds it difficult to insert the distal-end working unit12 through the trocar20 (seeFIG. 1). If the operator inactivates themanipulator10 and disconnects themotor40 and thepulley50afrom each other, then thewire52 is restored to an unstretched state, thus causing thepulley50ato turn clockwise.

According to the present invention, as shown inFIG. 12, therotor300 and thepulley50aare turned further counterclockwise. At time t2 (seeFIG. 10), thepulley50ais turned beyond the origin P0 through an angle corresponding to the error ε, and therotor300 reaches the origin P0, thereby fully closing thegripper59. At this time, the control command of thecontroller514 represents a virtual position, which is angularly spaced from the closed position of thegripper59, by an angle corresponding to the error ε (see thegripper59 shown in imaginary lines inFIG. 12).

Although thegripper59 is now closed, thepulley50ais further turned counterclockwise to reach the first control target value P1, in order to fully close thegripper59 in view of various control errors (see themarker302 shown in imaginary lines inFIG. 12).

Thegripper59 is now fully closed. Since the first control target value P1 is smaller than the limit value Px, thewire52 and thegripper59 are prevented from being subjected to excessive forces, and the time required to perform the origin return process is shortened.

At this time, when themotor40 and thepulley50aare disconnected from each other, thewire52 is restored to its unstretched state. However, since thewire52 still undergoes a considerable amount of tension, the service life of thewire52 is shortened. Furthermore, inasmuch as both themotor40 and thepulley50aare not in their origins P0, themanipulator system500 may suffer from trouble, because replacement of the workingunit16 assumes that themotor40 and thepulley50aare in their origins P0. Specifically, it is physically difficult to remove the workingunit16 from the operatingunit14 and to mount another workingunit16 on the operatingunit14. Further, the software process for initializing the parameters based on the origin P0 becomes complex.

According to the present invention, as shown inFIG. 13, thepulley50aand therotor300 are turned clockwise in a direction to open thegripper59, until thepulley50aand therotor300 reach their origins P0. At this time, therotor300 is not actually turned, but remains at the origin P0, while thewire52 is restored to an unstretched state. Therefore, themotor40, thepulley50a,and therotor300 are stably held at their origin positions P0. When themotor40 and thepulley50aare disconnected from each other, since the tension of thewire52 is essentially nil, or at its initial level, therotor300 and thepulley50aare not moved. Therefore, the service life of thewire52 can be increased.

According to the present embodiment, as described above, the first control target value P1 indicative of the virtual position is issued to cause thegripper59 to reach the origin P0 at an end of the operating range thereof. Therefore, the gripper or theactuating unit59 can reliably be returned to the origin without the need for an electric device, such as a sensor in combination with thegripper59. At this time, since stresses remain and are not removed from thegripper59, themotor40, and thewire52, the second control target value P2 indicative of the origin P0 is subsequently issued in order to remove such stresses.

Although thegripper59 and thepulley50aare operatively connected to each other by thewire52, which inevitably experiences stretching, and by various parts of the manipulator which cause friction, thegripper59 can accurately be returned to its origin position, thereby eliminating the error ε.

Since the origin P0 of thegripper59 is the closed position of thegripper59, the operator can visually confirm with ease the return of thegripper59 to its origin. The operator thus finds it easy to insert the fully closed gripper59 through thetrocar20.

Themotor40 is associated with theangle sensor43 for detecting an angular displacement thereof. During the first-stage origin return process, thecontroller514 monitors the detected value from theangle sensor43. After having confirmed that themotor40 has reached the first control target value P1, thecontroller514 starts the second-stage origin return process. Since themotor40 reliably reaches the first control target value P1, the error ε of thegripper59 is reliably eliminated.

Since no electric components are included in the workingunit16, the workingunit16 that has been removed from the operatingunit14 can easily be cleaned and sterilized.

Thecontroller514 may change the first control target value P1 depending on the type of workingunit16, which is provided by theID relay unit106. Therefore, thecontroller514 can appropriately control the workingunit16 based on the type of workingunit16.

The workingunit16 has been described as being connected to a manuallyoperable operating unit14. However, the workingunit16 may also be applied to asurgical robot system700, as shown inFIG. 14, for example.

Thesurgical robot system700 has an articulatedrobot arm702 and aconsole704, with the workingunit16 being connected to the distal end of therobot arm702. The distal end of therobot arm702 incorporates a mechanism therein, which is the same as theactuator block30, for connecting and actuating the workingunit16. Themanipulator10 comprises therobot arm702 and the workingunit16. Therobot arm702 may comprise a means for moving the workingunit16, and is not limited to an installed type, but may be of an autonomous movable type. Theconsole704 may be a table type console, a control panel type console, or the like.

Therobot arm702 should preferably have six or more independent joints (rotary shafts, slide shafts, etc.) for setting the position and orientation of the workingunit16 as desired. Theactuator block30 on the distal end of therobot arm702 is integrally combined with adistal end708 of therobot arm702.

Therobot arm702 operates under the control of theconsole704, and may be actuated automatically according to a program, or by joysticks (robot operating units)706 mounted on theconsole704, or by a combination of the program and thejoysticks706. Theconsole704 includes and carries out the functions of thecontroller514.

Theconsole704 includes twojoysticks706 as an operating unit, exclusive of theactuator block30 of theabove operating unit14, and amonitor710. Although not shown, the twojoysticks706 are capable of individually operating tworobot arms702. The twojoysticks706 are disposed in respective positions where they can easily be operated by both hands of the operator. Themotor710 displays information, such as an image produced by an endoscope.

Thejoysticks706 can be moved vertically and horizontally, twisted, and tilted, and therobot arm702 can be moved depending on such movements of thejoysticks706.

Thejoysticks706 may be master arms. Therobot arm702 and theconsole704 may communicate with each other via a communication means comprising a wired link, a wireless link, a network, or a combination thereof.

Themanipulator system500 according to the present invention is not limited to medical use, but also is applicable to other fields, including the repair of various parts in small spaces utilized in energy systems or the like.

Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made to the embodiment without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A manipulator system comprising:

a manipulator having an actuator and an actuating unit, the actuating unit being actuatable by the actuator to change an attitude thereof; and

a controller for controlling the manipulator in order to perform an origin return process for moving the actuating unit to an end of an operating range thereof, by issuing a first control target value to the actuator indicative of a virtual position beyond the end of the operating range, and thereafter issuing a second control target value to the actuator indicative of the end of the operating range.

2. A manipulator system according toclaim 1, wherein the actuating unit comprises an openable and closable gripper mounted on a distal end of the manipulator, and the end represents a closed position of the gripper.

3. A manipulator system according toclaim 2, wherein the virtual position represents a position over from the end by a distance, which is greater than a value corresponding to an error between a target position of the actuating unit and an actual position thereof.

4. A manipulator system according toclaim 2, wherein the virtual position represents a position, which is smaller than a limit value for a control target value for the gripper, when the gripper operates in a normal process other than the origin return process.

5. A manipulator system according toclaim 1, wherein the actuator includes detecting means for detecting an operated position thereof, and the controller monitors a detected value from the detecting means, confirms that the actuator has reached the first control target value after having issued the first control target value, and then issues the second control target value.

6. A manipulator system according toclaim 1, wherein the manipulator comprises:

a first portion including the actuator and being connected to the controller; and

a second portion having the actuating unit on a distal end thereof and a proximal end detachably connected to the first portion;

the second portion including a driven member disposed in the proximal end thereof and engaging the actuator, and a transmitting member for transmitting power from the driven member to the actuating unit.

7. A manipulator system according toclaim 6, wherein the manipulator comprises a plurality of second portions each having an identifier indicative of the type thereof;

the first portion has identifying means for identifying the identifier of one of the second portions, which is mounted on the first portion, and supplying the type indicated by the identified identifier to the controller; and

the controller changes the virtual position depending on the type of the second portion that is supplied from the identifying means.

8. A method of controlling a manipulator having an actuating unit, which is actuatable by an actuator to change an attitude thereof, comprising:

performing an origin return process for moving the actuating unit to an end of an operating range thereof, by issuing a first control target value to the actuator indicative of a virtual position beyond the end of the operating range; and

thereafter issuing a second control target value to the actuator indicative of the end of the operating range.

9. A method according toclaim 8, wherein the actuating unit comprises an openable and closable gripper mounted on a distal end of the manipulator, and the end represents a closed position of the gripper.

10. A method according toclaim 9, wherein the virtual position represents a position over from the end by a distance, which is greater than a value corresponding to an error between a target position of the actuating unit and an actual position thereof.

11. A method according toclaim 10, wherein the virtual position represents a position, which is smaller than a limit value for a control target value for the gripper, when the gripper operates in a normal process other than the origin return process.

12. A method according toclaim 8, wherein the actuator includes detecting means for detecting an operated position thereof, and the controller monitors a detected value from the detecting means, confirms that the actuator has reached the first control target value after having issued the first control target value, and then issues the second control target value.

13. A method according toclaim 8, wherein the manipulator comprises:

the second portion including a driven member disposed in the proximal end thereof and engaging the actuator, and a transmitting member for transmitting movement from the driven member to the actuating unit.

14. A method according toclaim 13, wherein the manipulator comprises a plurality of second portions each having an identifier indicative of the type thereof;